Telephone-transmitter.



No. 721,708. PATENTED MAR.- s,- 1903.

- A. P. LAWSON.

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UNITED STATES PATENT OFFICE.

' ALBERT F. LAWSON, OF BUFFALO, NEW YORK, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, OF SEVEN-TWELFTHS TO RENSSELAER W. DANIELS, OF LOCKPORT, NEW YORK, AND JOHN ATKINS, OF BUF- FALO, NEW YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters PatentNo. 721,708, dated March 3, 1903. Application filed August 6, 1900. Renewed JunelS, 1902. Serial No. 111,568. (No modeL falo, in the county of Erie and State of New. York, (whose post-ofiice address is 449 West.

Ferry street, Bufiaio, New York,) have invented certain new and useful Improvements;

in Telephone-Transmitters; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to figures of reference marked thereon, which form a part of this specification.

My invention relates to improvements in telephone-transmitters, its object being to materiallyincrease the resonance and sensibility of the operative parts.

To that end my invention consists of a certain combination and arrangement of parts, to be more fully hereinafter described and claimed, by means of which the effect of the human voice in the form of sound-Waves is exerted against the back or inside face instead of the front or outside face of the diaphragm or diaphragms forming a part of the walls of the vocalizing-chambr'of the transmitter.

In the drawings, Figure 1 is a central longitudinal section of my improved transmittor. Fig. 2 is a side elevation, and Fig. 3 is an end elevation, of thesame.

Referring to the drawings, 1 is the casing, which forms a part of the vocalizing-chamber, preferably of cylindrical configuration.

2 2 are annular caps in screw-threaded engagement with the casing l and between which and the casing 1 are secured the vibrating diaphragms 3 3, which form the balance of the walls of the'vocalizing-chamber. The connections between the diaphragms 3 3 and the primary circuit are shown at 4 4.

5 5 are the carbon back plates secured cen-.

Between these back plates 5 5 is a loose fill-- ing of granular carbon 6, confined in such position by the wrapper 7, secured by the wires 8 to the back plates 5 5.

9 9 are metal frames secured to the caps 2 2 and adapted to hold centrally the screws 10 10, which have adjustable contact with the diaphragms for adjusting their vibrations.

11' is the mouthpiece secured in the casing 1 and forming a passage into the vocaiizingchamber between the two diaphragms.

In operation the sound-waves produced by the voice in the mouthpiece are thrown against the back or contact faces of the diaphragms instead of the front face, as in the diiferent forms of transmitters now in use. The first efiect of this action is to throw the diaphragms outwardly or away from the-interposed carbon back plates, thus first drawing the back plates 5 5 away from each other, the elasticity of the diaphragms restoring them to their former positions. This reversal of action has the'efiect of increasing the resonance and sensibility of the diaphragms,which increased effect is transmitted to the granular carbon between the back plates.-

By means of my improved construction a more delicate and finished action takes place, which enables the transmitter to be'successfully operated within a much wider range than obtains with the forms of transmitters now in use.

One diaphragm only could be employed; but I prefer the use of two,-as shown.

It will be seen that'the vocalizing-chamber is partly formed bytheldiaphragm, so that the sound-Wavesare conducted between the diaphragms and against their back or contact faces.

If only one diaphragm is used, the opposite side would be formed of a sheet or wall of suitable material. F

A telephone-transmitter consisting'of a casing which forms a part ofthe wall'softhe vocalizing-chamber, diaphragms which form the balance of the walls of the vocalizing-chamber, carbon back plates secured to the back or inside faces of the diaphragms, and granular carbon held between the carbon back name to this specification in the presence of plates, for receiving and transmitting the vitwo subscribing witnesses. brations of the diaphl'agms, and a mouthpiece in the casing which conducts the sound- ALBERT LAWSON 5 waves against the back or inside faces of the Witnesses:

diaphragms as and for the purpose stated. CHARLES P. FENCHTER,

In testimony whereof I have signed my W. T. MILLER. 

